This is different than getAnalysis in that it can fail (if the analysis results haven't been computed), so should only be used if you can handle the case when the analysis is not available. This method is often used by transformation APIs to update analysis results for a pass automatically as the transform is performed.

mustPreserveAnalysisID - This method serves the same function as getAnalysisIfAvailable, but works if you just have an AnalysisID.

This obviously cannot give you a properly typed instance of the class if you don't have the class name available (use getAnalysisIfAvailable if you do), but it can tell you if you need to preserve the pass at least.

This is called by Analyze to print out the contents of an analysis. Otherwise it is not necessary to implement this method. Beware that the module pointer MAY be null. This automatically forwards to a virtual function that does not provide the Module* in case the analysis doesn't need it it can just be ignored.

releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memory when it is no longer needed.

The default behavior of passes is to hold onto memory for the entire duration of their lifetime (which is the entire compile time). For pipelined passes, this is not a big deal because that memory gets recycled every time the pass is invoked on another program unit. For IP passes, it is more important to free memory when it is unused.

Optionally implement this function to release pass memory when it is no longer used.